1. Field of the Invention
The present inventive concept relates to a method of fabricating a nonvolatile memory device, and more particularly, to a method of fabricating a nonvolatile memory device using a resistive element.
2. Description of the Related Art
Examples of nonvolatile memory devices which use a resistance material may include a phase change random access memory (PRAM) device, a resistive random access memory (RRAM) device, and a magnetic random access memory (MRAM) device. Such nonvolatile memory devices which use a resistance material may store data by using variations in the state of a phase change material, for example, a chalcogenide alloy, variations in the resistance of a variable resistor, or variations in the resistance of a magnetic tunnel junction (MTJ) thin film with respect to the magnetization of a ferromagnetic material. Whereas Dynamic random access memory (DRAM) devices or flash memory devices may store data using charge.
For example, PRAM devices define a crystalline phase of a phase change material as a set state or a logic value of “0” and define the amorphous phase of a phase change material as a reset state or a logic value of “1.” This is due to the fact that a phase change material has a lower resistance in the crystalline phase and has a higher resistance in the amorphous state. In PRAM devices, a write pulse, for example, a set pulse and/or a reset pulse, may be provided to a phase change material, and data may be written to the phase change material with joule heat generated by the write pulse. For example, PRAM devices may apply a write pulse, for example, a set pulse and/or a reset pulse, to phase change materials and write data to the phase change materials using joule heat generated by the write pulse. PRAM devices may write a logic value of “1” to phase change materials by heating the phase change materials to their melting point or higher using a reset pulse and quickly cooling the phase change materials so that the phase change materials become amorphous. PRAM devices may write a logic value of “0” to phase change materials by heating the phase change materials to a temperature between the crystallization temperature and the melting point using a set pulse, and, then, maintaining the temperature of the phase change materials for a given amount of time so that the phase change materials may become crystalline.